In a number of applications it is important to remove oxygen from a mixture of gases. For example, even in purified gases, it is known that trace quantities of oxygen remain within the gas. In order to provide a very pure gas, it would be desirable to remove as much of the trace oxygen as possible. Examples of such gases include nitrogen and noble gases.
Small quantities of oxygen mixed within otherwise pure inert gases have proven problematic in a number of contexts. For example, in the manufacture of semiconductor devices, it is important to provide an essentially oxygen-free environment during certain types of processing steps. A typical solution for the problem is to flush the processing environment with an inert gas. However, even when inert gas fills the processing environment, trace amounts of oxygen still exist and are mixed with the inert gases.
Various processes have been attempted to remove oxygen from such inert gases. For example, it has been conventional to filter the gas in order to attempt to remove oxygen. Various filtering and removal processes have been employed, including adsorption, absorption, catalytic reactions, and membrane separation. Even using these processes, however, gases of less than ideal purity have been produced. Thus, there is a need in the art to be able to remove oxygen from gaseous mixtures and to obtain an oxygen-free environment.
A reverse of the problem described above is involved in the production of commercial quantities of extremely pure oxygen. Problems similar to those described concerning other gases are also encountered in the production of pure oxygen. In all existing processes, it would be desirable to provide oxygen of better quality using a simple and relatively inexpensive process.
It would also be desirable to provide extremely pure oxygen at high pressure, such as pressures greater than 500 psig. Conventional mechanical compressors used to provide high pressure gases require reciprocating pistons. There are at least three significant disadvantages associated with conventional mechanical compressors: (1) there is a tendency for the compressed gas to become contaminated with oils or lubricants required to overcome the friction between close contact moving parts, along with some metals; (2) there reciprocating motion can cause unacceptable vibration and noise in certain environments, such as hospitals, aerospace, and outer space applications, and (3) the energy required by a conventional compressor is far greater than ion conduction. Thus, there is a need in the art for extremely high pressure oxygen which is obtained without a high energy consuming mechanical action conventional compressor.
The copending patent applications referenced above disclose apparatus and methods which effectively remove oxygen from a gaseous mixture and which are able to provide a source of pure oxygen. Oxygen ion conducting electrolytes made from doped ceramic oxide materials are used in the disclosed apparatus and methods. When relatively pure gases are being processed to remove trace quantities of oxygen, it is possible to reduce the ceramic oxide and cause permanent damage the ceramic.
Accordingly, it would be a significant advancement in the art to provide an apparatus and method for removing oxygen from gaseous mixtures and to obtain an oxygen-free environment which includes a system to prevent damage to ceramic oxide materials used herein. It would also be an advancement in the art to provide pure, high pressure oxygen without the mechanical action of conventional compressors.
Such methods and apparatus are disclosed and claimed herein.